This invention relates generally to the production of gaskets and similar parts and deals more specifically with a machine for forming and handling such parts.
The mass production of gaskets and similar thin parts is carried out by a die cutting process employing usually one of two types of cutting apparatus. One is a steel rule cutting tool having a knife edge and which is reciprocated against the gasket material on a first support surface to cut the gaskets; the other is a punching assembly which consists of interfitting male and female dies, one of which may be reciprocated against the other to cut the gasket material at the mating edges of the dies. Either of the foregoing cutting devices are presently used in large, open back, inclined mechanical presses which were originally developed for stamping parts out of relatively thick sheets of metal and printing presses especially adapted for manufacturing gaskets. Since gaskets and similar parts are formed from cork, rubber, foam, asbestos, and other materials that are soft in comparison to thick metal sheets, these metal forming machines have not been particularly successful in efficiently forming gaskets.
A major drawback has been the slowness with which existing machines operate. Cranks are typically provided in this type of equipment to effect a power stroke that is fixed in length. The stroke is usually between 4 and 6 inches which is unnecessarily long for cutting gaskets from relatively soft material, and the speed at which the machine operates is restricted accordingly. The excessively long power stroke in combination with the inherently slow operation of the crank mechanism limits the conventional punch press to an operating speed that is usually less than 80 strokes per minute. In addition, the force of the stroke in these machines typically ranges from 10 to 100 tons which is considerably more powerful than is needed to cut soft gasket material. Therefore, the cutting dies and other working components of the machine wear out relatively quickly.
Existing equipment is further unsatisfactory due to its inability to cut with the precision that is required for gaskets and like parts. This problem is compounded because of the tendency of the cutting dies to quickly become dull and worn, as previously indicated. In the case of the steel rule die, uniformly accurate cutting of the gasket material is also difficult to achieve because the ram which performs the cutting stroke is often misaligned with respect to the striker plate against which it acts. Shims are frequently used in an effort to maintain the striker plate oriented properly to the ram, and the accuracy resulting from this arrangement falls far short of that required for precision cutting of gaskets.
In most cases the gasket material is fed through existing machines by hand. This of course further detracts from the operating speed and also results in the waste of a substantial amount of material. Despite the skill or experience of the machine operator, the strip material cannot be manually fed in a manner to cut successive gaskets as closely together as possible in order to minimize the scrap. The manual feeding procedure is also unsatisfactory from a safety standpoint because the hands of the machine operator must be placed near the cutting die in order to pull the material through the machine by hand. Even those machines that are equipped with mechanical feed mechanisms require excessive time to set up so that it is impractical to utilize the mechanical feed unless a large number of parts are to be run. These existing feed devices are also unable to advance the gasket material in accurate length increments at high rates of speed and are costly to construct and maintain.
The handling of the gaskets after they have been cut has been an additional problem that has substantially increased the production time and the labor costs. The gaskets are usually removed by hand from the strip of material from which they are cut. This involved the knocking out of the gaskets and slug material, disposal of the scrap, counting of the gaskets, and the arranging of the gaskets in stacks, all of which is normally done by hand.
In view of the aforementioned difficulties associated with existing gasket producing equipment, there is a need for an improved machine that is able to efficiently and economically form gaskets and similar parts. It is the primary goal of the present invention to meet that need.
More specifically, it is an important object of the present invention to provide a machine that operates to cut gaskets and similar parts with increased precision as compared to existing equipment.
Another important object of the present invention is to provide a machine of the character described that operates at a high rate of speed in order to minimize the production time.
Still another object of the invention is to provide a machine of the character described that includes means for accurately adjusting the length and pressure of the power stroke that effects cutting of the gaskets. Adjustment of the stroke length to the minimum travel maximizes the speed at which the machine can operate, while setting the pressure of the stroke as small as possible decreases the wear on the cutting dies and tools and thus increases their useful life.
A further object of the invention is to provide a machine of the character described wherein the cutting dies remain parallel at all times, thereby assuring uniformly accurate cutting of the parts and adding to the life of the dies and tools.
An additional object of the invention is to provide a machine of the character described that is equipped with an automatic feed mechanism which advances the gasket material in accurately controlled length increments. This close control of the length of feed maximizes the number of parts that are formed from the material and permits the knocking out and stacking of the parts to be accurately carried out.
Yet another object of the invention is to provide a machine of the character described wherein the feed mechanism is able to receive and advance even short strips of material without detracting significantly from its operating speed.
A still further object of the invention is to provide a machine of the character described in which the feed mechanism may be quickly and easily set up for operation.
An additional object of the invention is to provide a machine of the character described that includes means for counting the parts that are formed and for arranging them in stacks containing a preselected number.
Another object of the invention is to provide a machine of the character described that is adapted to utilize cutting die sets of various sizes and shapes which may be easily installed and removed.
A further object of the invention is to provide a machine of the character described which operates with low power requirements.
Still another object of the invention is to provide a machine of the character described that is economical to construct and maintain.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.